(1) Field of the Invention
The present invention pertains to a pallet unstacker/stacker that can receive a stack of skewed or misaligned pallets on a conveyor of the dispenser, raise all but the bottom most pallet in the stack, square or straighten the bottom pallet and then dispense the straightened pallet from the dispenser, lower the remaining stack of pallets onto the conveyor and again raise all but the bottom most pallet in the stack to repeat the straightening step and dispensing step of operation of the dispenser. The operation of the device could also be reversed to stack pallets received by the device from a separate conveyor. All of the component parts of the stacker/unstacker are supported on a unitary, transportable frame that enables the pallet unstacker/stacker to be shipped in conventional cargo containers and also enables the pallet unstacker/stacker to be easily incorporated into existing pallet conveyor systems.
(2) Description of the Related Art
There are many different known types of pallet constructions that are employed in supporting goods when being shipped. The pallets are designed to be lifted by conventional forklift trucks and provide a base for large goods or for large numbers of goods that could not be manually lifted and transported. By supporting large, heavy goods or large numbers of goods on a pallet, the goods can be easily transported, for example, from a loading dock to a truck bed or vice versa, by a conventional forklift truck.
Most conventional pallets are constructed of wood and/or plastic and are intended to be reused several times. Returned pallets are usually stacked upon each other until they are needed. Often the stacking of the used pallets is done manually, resulting in skewing or misalignment of the pallets in many instances. What is meant by skewing or misalignment is that the sides of the pallets in the stack are not aligned and adjacent pallets are staggered or slightly turned relative to each other.
The skewing or misalignment of stacked pallets presents a problem to many known pallet dispensing apparatus. The typical prior art pallet dispensing apparatus is designed to receive a stack of pallets where the skewing or misalignment is minimal. If pallets stacked on each other are skewed to the extent that a corner of a misaligned pallet will project outwardly a small distance, for example approximately one to three inches, from the sides of the pallet stack the misalignment may prevent the stack from being loaded into the dispensing apparatus. When this occurs, the stack of pallets must be manually restacked so that the skewing of adjacent pallets is not so severe and so the restacked pallets may be loaded into the pallet dispensing apparatus.
Many known pallet dispensing apparatus are provided with templates that are employed to determine if the skewing of the stacked pallets is too severe to prevent them from being loaded into the dispensing apparatus. For example, if a stack of pallets cannot be passed through the template by a forklift without engaging the opposite sides of the template, then the skewing of the stack is too severe and the stack must be manually restacked to eliminate the skewing.
Many known pallet unstackers employ a pair of opposed arms that extend along opposite sides of a pallet stack supported by a conveyor and lift all but the bottom most pallet which is then moved on or dispensed by the conveyor. These prior art pallet dispensers do not include a mechanism for straightening the bottom pallet of the stack that is placed onto the conveyor. Therefore, care must be taken to ensure that the bottom pallet of the stack is placed on the conveyor in a sufficiently straightened orientation that will enable it to pass through the dispenser as the remaining pallets are unstacked and also to pass through the remainder of the pallet conveyor. If pallets in a stack are skewed or staggered, because the prior art dispenser or unstacker does not have a mechanism for straightening the pallets, it may be necessary to manually unstack and restack the pallets eliminating the skewed or staggered pallets in the stack. This results in lost time in unstacking pallets on the conveyor system and in increased costs for the labor involved in the manual unstacking and restacking of the pallets.
The disadvantages of prior art pallet straighteners can be overcome by a pallet unstacker/stacker that can easily be adjusted to straighten and dispense stacks of pallets of different sizes and which will still operate properly even if the stack of pallets loaded into the pallet unstacker/stacker are misaligned.